Singlet molecular oxygen (typically referred to as 1O2, specifically the a1Δg state of O2) can be an oxidant in chemistry, biology, and medicine; it can also be the energy source for chemical oxygen/iodine lasers. Methods for preparation of singlet oxygen include photosensitized excitation of ground state oxygen, and chemical generation of 1O2 by the reaction of bleach and hydrogen peroxide. Other methods include decomposition of unstable metal peroxides, organic endoperoxides, phosphite ozonides, or silyl hydrotrioxides, and decomposition of aqueous hydrogen peroxide by chlorine, as well as molybdate and other transition metal ions.